Currently the Internet has only one level of name resolution, DNS, which converts user-level domain names into IP addresses. In this paper we borrow liberally from the literature to argue that there should be three levels of name resolution: from user-level descriptors to service identifiers; from service identifiers to endpoint identifiers; and from endpoint identifiers to IP addresses. These additional levels of naming and resolution (1) allow services and data to be first class Internet objects and (2) facilitate mobility and provide an elegant way to integrate middleboxes into the Internet architecture. We further argue that flat names are a natural choice for the service and endpoint identifiers. Hence, this architecture requires scalable resolution of flat names, a capability that distributed hash tables (DHTs) can provide.

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IP networks today require massive effort to configure and manage. Ethernet is vastly simpler to manage, but does not scale beyond small local area networks. This paper describes an alternative network architecture called SEATTLE that achieves the best of both worlds: The scalability of IP combined with the simplicity of Ethernet. SEATTLE provides plug-and-play functionality via flat addressing, while ensuring scalability and efficiency through shortest-path routing and hash-based resolution of host information. In contrast to previous work on identity-based routing, SEAT-TLE ensures path predictability and stability, and simplifies network management. We performed a simulation study driven by real-world traffic traces and network topologies, and used Emulab to evaluate a prototype of our design based on the Click and XORP open-source routing platforms. Our experiments show that SEAT-TLE efficiently handles network failures and host mobility, while reducing control overhead and state requirements by roughly two orders of magnitude compared with Ethernet bridging.

The Web relies on the Domain Name System (DNS) to resolve the hostname portion of URLs into IP addresses. This marriage-of-convenience enabled the Web's meteoric rise, but the resulting entanglement is now hindering both infrastructures---the Web is overly constrained by the limitations of DNS, and DNS is unduly burdened by the demands of the Web. There has been much commentary on this sad state-of-affairs, but dissolving the illfated union between DNS and the Web requires a new way to resolve Web references. To this end, this paper describes the design and implementation of Semantic Free Referencing (SFR), a reference resolution infrastructure based on distributed hash tables (DHTs).

Today an application developer using a distributed hash table (DHT) with n nodes must choose a DHT protocol from the spectrum between O(1) lookup protocols [9, 18] and O(log n) protocols [20–23,25,26]. O(1) protocols achieve low latency lookups on small or low-churn networks because lookups take only a few hops, but incur high maintenance traffic on large or high-churn networks. O(log n) protocols incur less maintenance traffic on large or highchurn networks but require more lookup hops in small networks. Accordion is a new routing protocol that does not force the developer to make this choice: Accordion adjusts itself to provide the best performance across a range of network sizes and churn rates while staying within a bounded bandwidth budget. The key challenges in the design of Accordion are the algorithms that choose the routing table’s size and content. Each Accordion node learns of new neighbors opportunistically, in a way that causes the density of its neighbors to be inversely proportional to their distance in ID space from the node. This distribution allows Accordion to vary the table size along a continuum while still guaranteeing at most O(log n) lookup hops. The user-specified bandwidth budget controls the rate at which a node learns about new neighbors. Each node limits its routing table size by evicting neighbors that it judges likely to have failed. High churn (i.e., short node lifetimes) leads to a high eviction rate. The equilibrium between the learning and eviction processes determines the table size. Simulations show that Accordion maintains an efficient lookup latency versus bandwidth tradeoff over a wider range of operating conditions than existing DHTs.

The emergence of computationally-enabled sensors and the applications that use sensor data introduces the need for a software infrastructure designed specifically to enable the rapid development and deployment of applications that draw upon data from multiple, heterogeneous sensor networks. We present the Hourglass infrastructure, which addresses this need. Hourglass is an Internet-based infrastructure for connecting a wide range of sensors, services, and applications in a robust fashion. In Hourglass, a stream of data elements is routed to one or more applications. These data elements are generated from sensors inside of sensor networks whose internals can be entirely hidden from participants in the Hourglass system. The Hourglass infrastructure consists of an overlay network of well-connected dedicated machines that provides service registration, discovery, and routing of data streams from sensors to client applications. In addition, Hourglass supports a set of in-network services such as filtering, aggregation, compression, and buffering stream data between source and destination. Hourglass also allows third party services to be deployed and used in the network. In this paper, we present the Hourglass architecture and describe our test-bed and implementation. We demonstrate how our design maintains streaming data flows in the face of disconnection, allows discovery of and access to data from sensors, supports participants of widely varying capabilities (servers to PDAs), takes advantage of wellprovisioned, well-connected machines, and provides separate efficient communication paths for short-lived control messages and long-lived stream-oriented data. 1

Spam, by overwhelming inboxes, has made email a less reliable medium than it was just a few years ago. Spam filters are undeniably useful but unfortunately can flag non-spam as spam. To restore email’s reliability, a recent spam control approach grants quotas of stamps to senders and has the receiver communicate with a wellknown quota enforcer to verify that the stamp on the email is fresh and to cancel the stamp to prevent reuse. The literature has several proposals based on this general idea but no complete system design and implementation that: scales to today’s email load (which requires the enforcer to be distributed over many hosts and to tolerate faults in them), imposes minimal trust assumptions, resists attack, and upholds today’s email privacy. This paper describes the design, implementation, analysis, and experimental evaluation of DQE, a spam control system that meets these challenges. DQE’s enforcer occupies a point in the design spectrum notable for simplicity: mutually untrusting nodes implement a storage abstraction but avoid neighbor maintenance, replica maintenance, and heavyweight cryptography. 1

CiteSeer is a well-known online resource for the computer science research community, allowing users to search and browse a large archive of research papers. Unfortunately, its current centralized incarnation is costly to run. Although members of the community would presumably be willing to donate hardware and bandwidth at their own sites to assist CiteSeer, the current architecture does not facilitate such distribution of resources. OverCite is a design for a new architecture for a distributed and cooperative research library based on a distributed hash table (DHT). The new architecture harnesses donated resources at many sites to provide document search and retrieval service to researchers worldwide. A preliminary evaluation of an initial OverCite prototype shows that it can service more queries per second than a centralized system, and that it increases total storage capacity by a factor of n/4 in a system of n nodes. OverCite can exploit these additional resources by supporting new features such as document alerts, and by scaling to larger data sets.

This paper describes and evaluates Fireflies, a scalable protocol for supporting intrusion-tolerant network overlays. While such a protocol cannot distinguish Byzantine nodes from correct nodes in general, Fireflies provides correct nodes with a reasonably current view of which nodes are live, as well as a pseudo-random mesh for communication. The amount of data sent by correct nodes grows linearly with the aggregate rate of failures and recoveries, even if provoked by Byzantine nodes. The set of correct nodes form a connected submesh; correct nodes cannot be eclipsed by Byzantine nodes. Fireflies is deployed and evaluated on PlanetLab. 1.